Bending machines have a bending device comprising a bending die or matrix and a bend arm, both rotating about an axis and being provided with co-operating counteracting members. These counteracting members clamp a section of a workpiece immediately after the section to be bent, according to a feeding direction of the workpiece in the bending machine. The workpiece is bent by causing both the matrix and the bend arm to move around the axis from an initial position to an end position. When a bending operation ends, the matrix is caused to return to its initial position.
Conventionally, a mechanism that is built-in or connected to a stationary part of the bending machine causes the matrix to return to its initial position. This implies some drawbacks, which are joined to the fact that said mechanism outside the bend arm might interfere with the bending operation.